U.S. patent application number 16/348343 was filed with the patent office on 2020-03-05 for imaging with curved compression elements.
This patent application is currently assigned to Hologic, Inc.. The applicant listed for this patent is HOLOGIC, INC.. Invention is credited to Biao CHEN, Christopher RUTH, Timothy R. STANGO, Jay A. STEIN.
Application Number | 20200069274 16/348343 |
Document ID | / |
Family ID | 60002146 |
Filed Date | 2020-03-05 |
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United States Patent
Application |
20200069274 |
Kind Code |
A1 |
STANGO; Timothy R. ; et
al. |
March 5, 2020 |
IMAGING WITH CURVED COMPRESSION ELEMENTS
Abstract
A curved compression element, such as a breast compression
paddle, and imaging systems and methods for use with curved
compression elements. A system may include a radiation source, a
detector, and a curved compression element. Operations are
performed that include receiving image data from the detector;
accessing a correction map for the at least one compression paddle;
correcting the image data based on the correction map to generate a
corrected image data; and generating an image of the breast based
on the corrected image data. The breast compression element
generally has no sharp edges, but rather has smooth edges and
transitions between surfaces. The breast compression paddle also
includes a flexible material that spans a portion of a curved
bottom surface of the breast compression paddle to define a gap.
The flexible material may be a thin-film material such as a shrink
wrap.
Inventors: |
STANGO; Timothy R.;
(Marlborough, MA) ; STEIN; Jay A.; (Marlborough,
MA) ; CHEN; Biao; (Marlborough, MA) ; RUTH;
Christopher; (Marlborough, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HOLOGIC, INC. |
Marlborough |
MA |
US |
|
|
Assignee: |
Hologic, Inc.
Marlborough
MA
|
Family ID: |
60002146 |
Appl. No.: |
16/348343 |
Filed: |
September 25, 2017 |
PCT Filed: |
September 25, 2017 |
PCT NO: |
PCT/US2017/053311 |
371 Date: |
May 8, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62531807 |
Jul 12, 2017 |
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62419336 |
Nov 8, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 6/4441 20130101;
A61B 6/502 20130101; A61B 6/4411 20130101; A61B 6/4452 20130101;
A61B 6/4423 20130101; A61B 6/4233 20130101; A61B 6/0414 20130101;
A61B 6/5258 20130101; A61B 6/582 20130101; A61B 6/025 20130101;
A61B 6/4447 20130101 |
International
Class: |
A61B 6/00 20060101
A61B006/00; A61B 6/04 20060101 A61B006/04; A61B 6/02 20060101
A61B006/02 |
Claims
1. A breast compression paddle for use in an imaging system, the
breast compression paddle comprising: a curved right surface; a
curved left surface; a curved bottom surface; a curved front
surface; a top surface; and a flexible material in contact with the
curved right surface, the curved left surface, the curved front
surface, and the top surface, wherein the flexible material is
spaced apart from at least a portion of the curved bottom
surface.
2. The breast compression paddle of claim 1, wherein the flexible
material surrounds the curved right surface, the curved left
surface, the curved bottom surface, and the top surface.
3. The breast compression paddle of claim 1 or 2, wherein the
flexible material further surrounds the curved front surface.
4. The breast compression paddle of any of claims 1-3, further
comprising a back surface connected to each of the curved right
surface, the curved left surface, the curved front surface, and the
top surface.
5. The breast compression paddle of claim 4, wherein the curved
right surface and the curved left surface have a semicylindrical
shape having a height defined by the back surface and the curved
front surface.
6. The breast compression paddle of claim 4 or 5, further
comprising a gas inlet port disposed in the back surface for
receipt of a gas, and wherein at least a portion of one surface of
the breast compression paddle defines an opening in fluidic
communication with the gas inlet port.
7. The breast compression paddle of any of claims 1-6, wherein the
top surface is substantially flat.
8. The breast compression paddle of any of claim 1-3 or 7, further
comprising a back surface and a bracket attached to the back
surface, wherein the bracket is configured to mount the breast
compression paddle to the imaging system.
9. The breast compression paddle of any of claims 1-8, wherein the
flexible material spans from the curved right surface to the curved
left surface such that a gap is defined between at least the
portion of the curved bottom surface and a portion of the flexible
material spaced apart from the curved bottom surface.
10. The breast compression paddle of any of claims 1-9, wherein the
flexible material is configured to contact the curved bottom
surface when compressed against a breast.
11. The breast compression paddle of any of claims 1-10, wherein
the flexible material is a shrink-wrap material.
12. A breast compression paddle for use in an imaging system, the
breast compression paddle comprising: a curved right surface; a
curved left surface; a curved bottom surface; a curved front
surface; a top surface; and a transition between adjacent ones of
the curved right surface, the curved left surface, the curved
bottom surface, the curved front surface, and the top surface,
wherein all transitions include no sharp edges.
13. The breast compression paddle of claim 12, further comprising a
flexible material spanning from the curved right surface to the
curved left surface across a concave portion of the curved bottom
surface.
14. The breast compression paddle of claim 13, wherein an air gap
is defined between the concave portion of the curved bottom surface
and the flexible material.
15. The breast compression paddle of any of claims 13-14, wherein
the flexible material surrounds the curved right surface, the
curved left surface, the curved bottom surface, and the top
surface.
16. The breast compression paddle of claim 15, wherein the flexible
material further surrounds the curved front surface.
17. The breast compression paddle of any of claims 12-16, further
comprising a back surface connected to each of the curved right
surface, the curved left surface, the curved front surface, and the
top surface.
18. The breast compression paddle of any of claims 12-16, further
comprising a back surface, wherein the curved right surface and the
curved left surface have a substantially semicylindrical shape
having a height defined by the back surface and the curved front
surface.
19. The breast compression paddle of claim 17 or 18, further
comprising a gas inlet port disposed in the back surface for
receipt of a gas, and wherein at least a portion of one surface of
the breast compression paddle defines an opening in fluidic
communication with the gas inlet port.
20. The breast compression paddle of any of claims 12-19, wherein
the top surface is at least one of substantially flat and curved
similarly to the curved bottom surface.
21. The breast compression paddle of any of claims 12-20, further
comprising a back surface and a bracket attached to the back
surface, wherein the bracket is configured to mount the breast
compression paddle to the imaging system.
22. The breast compression paddle of any of claims 13-16, wherein
the flexible material spans from the curved right surface to the
curved left surface such that a gap is defined between at least a
portion of the curved bottom surface and the flexible material.
23. The breast compression paddle of any of claim 13-16 or 22,
wherein the flexible material is configured to contact the curved
bottom surface when compressed against a breast.
24. The breast compression paddle of any of claim 13-16 or 22-23,
wherein the flexible material is a shrink-wrap material.
25. An imaging system comprising: an imaging source; an imaging
receptor; and a breast compression element comprising: a plurality
of curved side surfaces; a front surface connected to each of the
plurality of curved side surfaces with a smooth transition between;
a compression surface connecting the plurality of curved side
surfaces; and a non-compression surface disposed opposite the
compression surface and connecting the plurality of curved side
surfaces.
26. The imaging system of claim 25, wherein the breast compression
element comprises a paddle removable from the imaging system.
27. The imaging system of claim 25, wherein the breast compression
element comprises a breast support platform.
28. The imaging system of claim 25, 26, or 27, wherein the breast
compression element is at least partially hollow.
29. The imaging system of any of claims 25-28, wherein the imaging
receptor is disposed in the breast compression element.
30. The imaging system of any of claims 25-29, wherein the imaging
receptor is movably disposed in the breast compression element.
31. The imaging system of any of claims 25-30, wherein the breast
compression element comprises a plurality of breast compression
elements.
32. The imaging system of any of claims 25-31, wherein the imaging
source is configured to move along an imaging arc having a center
point, and wherein an arc shape of the compression surface has a
center point at substantially the same location as the center point
of the imaging arc.
33. A system for imaging a breast, the system comprising: a
radiation source; at least one compression paddle having a
non-planar compression surface, wherein the at least one
compression paddle is configured to compress the breast during
imaging of the breast; a detector configured to detect radiation
emitted from the radiation source after passing through the at
least one compression paddle and the breast, wherein the detector
includes a plurality of pixels; and a memory and a processor
operatively connected to the detector, wherein the memory stores
instructions that, when executed by the processor, perform a set of
operations, the operations comprising: receiving image data from
the detector; accessing a correction map for the at least one
compression paddle; correcting the image data based on the
correction map to generate a corrected image data; and generating
an image of the breast based on the corrected image data.
34. The system of claim 33, wherein the operations further comprise
at least two of the following operations: upscaling the correction
map based on an image size for the image; modifying the correction
map by applying a squeeze factor; modifying the correction map for
a projection angle and a paddle shift; and modifying the correction
map based on a magnification.
35. The system of claim 34, wherein modifying the correction map
based on magnification is based at least in part on a height of the
compression paddle.
36. The system of any of claims 33-35, wherein the correction map
is represented as a matrix, wherein the elements of the matrix
represent correction values for a corresponding pixel of the
detector.
37. The system of claim 36, wherein the elements of the matrix
include values for scaling a brightness value of the corresponding
pixel of the detector.
38. The system of any of claims 33-37, wherein correcting the image
data includes correcting the image data on a pixel-by-pixel
level.
39. The system of any of claims 33-38, wherein the operations
further comprise further correcting a chest-wall area of the image
representative of an area within about 2 cm of a chest wall.
40. The system of claim 39, wherein correcting the chest-wall area
of the image includes determining a delta value based on at least
slope value and a threshold value.
41. The system of any of the claims 33-40, wherein the correction
map is generated by a process comprising: filling the compression
paddle with a liquid to create a filled paddle; placing the filled
paddle on a substantially radiolucent surface, wherein the
radiolucent surface covers an imaging area of a detector; passing
radiation through the filled paddle and substantially radiolucent
surface; detecting the radiation passed through the filled paddle
and substantially radiolucent surface; generating a correction
image based on the detected radiation; identifying an average pixel
value over the correction image; and generating the correction map
by dividing each pixel in the correction image by the average pixel
value.
42. The system of claim 41, wherein generating the correction map
further comprises generating a series of polynomial fits to
represent the correction map.
43. A method comprising: filling a hollow paddle with a liquid to
create a filled paddle; placing the filled paddle on a
substantially radiolucent surface, wherein the radiolucent surface
covers an imaging area of a detector; passing radiation through the
tilled paddle and substantially radiolucent surface; detecting the
radiation passed through the filled paddle and substantially
radiolucent surface; generating a correction image based on the
detected radiation; identifying an average pixel value over the
correction image; and generating a correction map by dividing each
pixel in the correction image by the average pixel value.
44. The method of claim 43, wherein the method further comprises
generating a series of polynomial tits to represent the correction
map.
45. The method of claim 44, wherein generating the series of
polynomial fits comprises: for each image column (x) of the
detector, selecting points along rows (y) of the detector; and
fitting the selected points to a polynomial function to generate a
set of fitted points; and wherein generating the correction map
further includes generating a fitted image based on the fitted
points.
46. The method of claim 45, wherein the polynomial function is a
fourth-order polynomial.
47. The method of any of claims 45-46, wherein generating the
correction map further comprises: smoothing the fitted image using
a boxcar averaging method; and scaling down the fitted image using
decimation.
48. The method of any of claims 43-47, wherein the liquid is water
and the substantially radiolucent material is a Lucite block having
a thickness of approximately 4 cm.
49. A computer-implemented method for generating an image of a
breast, the method comprising: receiving image data from a
radiographic detector; accessing a correction map for at least one
compression paddle having a non-planar compression surface;
correcting the image data based on the correction map to generate
corrected image data; and generating the image of the breast based
on the corrected image data.
50. The method of claim 49, further comprising at least two of:
upscaling the correction map based on an image size for the image;
modifying the correction map by applying a squeeze factor;
modifying the correction map for a projection angle and a paddle
shift; and modifying the correction map based on a
magnification.
51. The method of any of claims 49-50, wherein the correction map
is a matrix, wherein the elements of the matrix represent
correction values for a corresponding pixel of the detector.
52. The method of any of claims 49-51, wherein correcting the image
data includes correcting the image data on a pixel-by-pixel level.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is being filed on 25 Sep. 2017, as a PCT
International application, and claims priority to: (1) U.S.
Provisional Application No. 62/419,336, titled "Breast Compression
Paddle" and filed on Nov. 8, 2016, and (2) U.S. Provisional
Application No. 62/531,807, titled "Image Processing For Curved
Paddles" and filed on Jul. 12, 2017, both of which are incorporated
by reference in their entireties.
BACKGROUND
[0002] A significant patient concern in mammography and breast
tomosynthesis is the discomfort the patient may feel when the
breast is compressed, typically between two rigid plastic surfaces,
with sufficient force to immobilize the breast and spread out the
breast tissues for x-ray imaging. Another significant challenge is
to ensure that the imaged field include the desired amount of
breast tissue. The reasons for using compression include: (1) to
make the breast thinner in the direction of x-ray flux and thereby
reduce patient radiation exposure from the level required to image
the thicker parts of a breast that is not compressed; (2) to make
the breast more uniform in thickness in the direction of x-ray flux
and thereby facilitate more uniform exposure at the image plane
over the entire breast image; (3) to immobilize the breast during
the x-ray exposure and thereby reduce image blurring; and (4) to
bring breast tissues out from the chest wall into the imaging
exposure field and thus image more tissue. As the breast is being
compressed, typically a technician manipulates the breast to
position it appropriately and counter the tendency that compression
has of pushing breast tissue toward the chest wall and out of the
image field.
[0003] Standard compression methods for mammography and
tomosynthesis use a movable, rigid clear plastic compression
paddle. The breast is placed on a breast support platform that
typically is flat, and the paddle is then compressed onto the
breast, usually while a technician or other health professional is
holding the breast in place and perhaps manipulates the breast to
ensure proper tissue coverage in the image receptor's field of view
and to help spread the breast.
SUMMARY
[0004] In an aspect, the technology relates to a system for imaging
a breast. The system includes a radiation source; at least one
compression paddle having a non-planar compression surface, wherein
the at least one compression paddle is configured to compress the
breast during imaging of the breast; a detector configured to
detect radiation emitted from the radiation source after passing
through the at least one compression paddle and the breast, wherein
the detector includes a plurality of pixels; and a memory and a
processor operatively connected to the detector, wherein the memory
stores instructions that, when executed by the processor, perform a
set of operations. The operations include receiving image data from
the detector; accessing a correction map for the at least one
compression paddle; correcting the image data based on the
correction map to generate a corrected image data; and generating
an image of the breast based on the corrected image data. In an
example, the operations further include at least two of the
following operations: upscaling the correction map based on an
image size for the image; modifying the correction map by applying
a squeeze factor; modifying the correction map for a projection
angle and a paddle shift; and modifying the correction map based on
a magnification. In another example, modifying the correction map
based on magnification is based at least in part on a height of the
compression paddle. In yet another example, the correction map is
represented as a matrix, wherein the elements of the matrix
represent correction values for a corresponding pixel of the
detector. In still yet another example, wherein the elements of the
matrix include values for scaling a brightness value of the
corresponding pixel of the detector.
[0005] In another example, correcting the image data includes
correcting the image data on a pixel-by-pixel level. In yet another
example, the operations further include further correcting a
chest-wall area of the image representative of an area within about
2 cm of a chest wall. In still yet another example, correcting the
chest-wall area of the image includes determining a delta value
based on at least a slope value and a threshold value.
[0006] In another example, the correction map is generated by a
process including: filling the compression paddle with a liquid to
create a filled paddle; placing the filled paddle on a
substantially radiolucent surface, wherein the radiolucent surface
covers an imaging area of a detector; passing radiation through the
filled paddle and substantially radiolucent surface; detecting the
radiation passed through the filled paddle and substantially
radiolucent surface; generating a correction image based on the
detected radiation; identifying an average pixel value over the
correction image; and generating the correction map by dividing
each pixel in the correction image by the average pixel value. In
yet another example, generating the correction map further
comprises generating a series of polynomial fits to represent the
correction map.
[0007] In another aspect, the technology relates to a method
including: filling a hollow paddle with a liquid to create a filled
paddle; placing the filled paddle on a substantially radiolucent
surface, wherein the radiolucent surface covers an imaging area of
a detector; passing radiation through the filled paddle and
substantially radiolucent surface; detecting the radiation passed
through the filled paddle and substantially radiolucent surface;
generating a correction image based on the detected radiation;
identifying an average pixel value over the correction image; and
generating a correction map by dividing each pixel in the
correction image by the average pixel value. In an example, the
method further comprises generating a series of polynomial its to
represent the correction map. In another example, generating the
series of polynomial fits comprises: for each image column (x) of
the detector, selecting points along rows (y) of the detector; and
fitting the selected points to a polynomial function to generate a
set of fitted points; and wherein generating the correction map
further includes generating a fitted image based on the fitted
points. In yet another example, the polynomial function is a
fourth-order polynomial. In still yet another example, generating
the correction map further comprises: smoothing the fitted image
using a boxcar averaging method; and scaling down the fitted image
using decimation. In another example, the liquid is water and the
substantially radiolucent material is a Lucite block having a
thickness of approximately 4 cm.
[0008] In yet another aspect, the technology relates to a
computer-implemented method for generating an image of a breast.
The method includes receiving image data from a radiographic
detector; accessing a correction map for at least one compression
paddle having a non-planar compression surface; correcting the
image data based on the correction map to generate corrected image
data; and generating the image of the breast based on the corrected
image data. In an example, the method further includes at least two
of: upscaling the correction map based on an image size for the
image; modifying the correction map by applying a squeeze factor;
modifying the correction map for a projection angle and a paddle
shift; and modifying the correction map based on a magnification.
In another example, the correction map is a matrix, and the
elements of the matrix represent correction values for a
corresponding pixel of the detector. In yet another example,
wherein correcting the image data includes correcting the image
data on a pixel-by-pixel level.
[0009] In one aspect, the technology relates to a breast
compression paddle for use in an imaging system, the breast
compression paddle having: a curved right surface; a curved left
surface; a curved bottom surface; a curved front surface; a top
surface; and a flexible material in contact with the curved right
surface, the curved left surface, the curved front surface, and the
top surface, wherein the flexible material is spaced apart from at
least a portion of the curved bottom surface.
[0010] In one aspect, the technology relates to a breast
compression paddle for use in an imaging system, the breast
compression paddle having: a curved right surface; a curved left
surface; a curved bottom surface; a curved front surface; a top
surface; and a transition between adjacent ones of the curved right
surface, the curved left surface, the curved bottom surface, the
curved front surface, and the top surface, wherein all transitions
include no sharp edges.
[0011] In one aspect, the technology relates to an imaging system
having: an imaging source; an imaging receptor; and a breast
compression element having: a plurality of curved side surfaces; a
front surface connected to each of the plurality of curved side
surfaces with a smooth transition between; a compression surface
connecting the plurality of curved side surfaces; and a
non-compression surface disposed opposite the compression surface
and connecting the plurality of curved side surfaces.
[0012] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used to limit the scope of the claimed
subject matter.
BRIEF DESCRIPTION OF UTE DRAWINGS
[0013] FIG. 1A depicts a perspective view of a portion of an
upright breast x-ray imaging system.
[0014] FIG. 1B depicts a side elevation of the system of FIG.
IA.
[0015] FIG. 1C depicts a side elevation of an example of a tilting
imaging system.
[0016] FIG. 2 depicts a front elevation an imaging system showing
rotational movement of a radiation source.
[0017] FIG. 3A depicts a top perspective view of a breast
compression element.
[0018] FIG. 3B depicts a bottom perspective view of the breast
compression element of FIG. 3A.
[0019] FIG. 3C depicts a front view of the breast compression
element of FIG. 3A.
[0020] FIG. 3D depicts a back view of the breast compression
element of FIG. 3A.
[0021] FIG. 3E depicts a right side view of the breast compression
element of FIG. 3A.
[0022] FIG. 3F depicts a left side view of the breast compression
element of FIG. 3A.
[0023] FIG. 3G depicts a top view of the breast compression element
of FIG. 3A.
[0024] FIG. 3H depicts a bottom view of the breast compression
element of FIG. 3A,
[0025] FIG. 3I depicts an exploded perspective view of the breast
compression element of FIG. 3A.
[0026] FIG. 4A depicts a schematic view of an imaging system using
the breast compression element of FIGS. 3A-3I.
[0027] FIG. 4B depicts a perspective view of an imaging system of
FIG. 4A.
[0028] FIG. 5A depicts an example image without the image
processing techniques discussed herein.
[0029] FIG. 5B depicts an example image with the image processing
techniques discussed herein.
[0030] FIG. 6A depicts a method for generating a correction map for
image processing for curved paddles.
[0031] FIG. 6B depicts an example uncorrected image used for a
sample correction map.
[0032] FIG. 6C depicts an example corrected image based on the
sample correction map.
[0033] FIG. 7 depicts a method for image processing for curved
paddles.
[0034] FIG. 8 depicts a method for image processing for a paddle
providing inconsistent compression.
[0035] FIG. 9 depicts one example of a suitable operating
environment in which one or more of the present examples can be
implemented.
[0036] FIG. 10 depicts an example of a network in which the various
systems and methods disclosed herein may operate.
DETAILED DESCRIPTION
[0037] The present technology relates to a breast compression
element, such as a breast compression paddle or compression support
surface, for use in a breast imaging system. During imaging of a
breast, it is often desirable to immobilize the breast through
compression. For instance, by compressing the breast, the breast
can be made thinner requiring a lower dose of radiation. Further,
by immobilizing the breast, image blurring from movement of the
breast during imaging is reduced. Other benefits are also realized
by compressing the breast. The paddle commonly used to compress the
breast, however, may cause distortions in the imaging process as
x-rays must pass through the paddle. For instance, while the
compression paddles are generally made from at least partially
radiolucent materials, the shape and configuration of the
compression paddles may cause deflection, refraction, dispersion,
reflection, or other undesired interference with an x-ray beam as
it passes through the paddle. Thus, undesired artifacts may appear
in the resultant image or may need to be accounted for during image
processing.
[0038] The paddle may also cause discomfort to the patient whose
breast is being compressed. One reason for discomfort that the
patient may feel is that the compression force is non-uniformly
distributed throughout the breast. It is concentrated at the
thickest portion of the breast, usually near the chest wall, at or
near the lower front edge of the compression paddle and the upper
front corner of the breast platform. The anterior portion of the
breast, such as near the nipple, may receive less compressive
force, or no compressive force. The paddle may not even contact
this portion of the breast, (The terms front, lower, and upper
pertain to using a craniocaudal (CC) imaging orientation, with the
patient facing the front of the imaging system, although it should
be understood that other imaging orientations, including
mediolateral oblique (MLO) image orientations or views, are used
with the same equipment and these terms need to be adjusted
accordingly.)
[0039] To improve these issues relating to compression elements, in
part, the breast compression elements discussed herein reduce or
minimize sharp edges (e.g., no sharp edges), thus reducing image
blurring due to edge effects. Further, the breast compression
elements are shaped so as to have a more consistent thickness at
all angles during imaging. Additionally or alternatively, a thin
material spans a curved bottom surface of the breast compression
element to create a gap between at least a portion of the bottom
surface and the thin material. For example, the thin material may
be a flexible thin film material displaying very limited stretching
capability and strong tensile strength. As the breast compression
element is pressed against the breast, the flexible material
contacts the breast first so as to begin compression of the breast.
As compressive pressure increases, the flexible material is
deflected towards the curved bottom surface, providing a more
comfortable compression process for the patient. The design of the
breast compression structure also allows for more comfort and
support in imaging systems that allow patients to tilt against the
system.
[0040] FIGS. 1A-1C illustrate non-limiting examples of multi-mode
breast x-ray imaging systems operable in a computed tomography (CT)
mode but also configured to selectively operate in a tomosynthesis
mode, including a wide angle tomosynthesis mode and a narrow angle
tomosynthesis mode, as well as in a mammography mode. For clarity
of illustration, a patient shield for use in the CT mode is omitted
from FIGS. 1A-1B, but an example is illustrated in FIG. IC. A
support column 100 is secured to a floor and houses a motorized
mechanism for raising and lowering a horizontally extending axle
102, which protrudes through an opening 100a in column 100, and for
rotating axle 102 about its central axis. Axle 102 in turn supports
a coaxial axle 102a that can rotate with or independently of axle
102. Axle 102 supports a breast immobilization unit comprising an
upper compression element 104a and a lower compression element 104b
such that each compression element can move up and down along the
long dimension of support 100 together with axles 102 and 102a. At
least one of the compression elements can move toward the other,
and unit 104 can rotate about the common central axis of axles 102
and 102a. Either one or both of the upper compression element 104a
and the lower compression element 104b may incorporate the breast
compression element discussed herein and shown in FIGS. 3A-3I. The
breast compression element discussed herein is depicted in FIG. 1A
as in the upper position. In addition, axle 102 supports a gantry
106 for two types of motorized movement: rotation about the central
axis of axle 102, and motion relative to axle 102 along the length
of gantry 106. Gantry 106 carries at one end an x-ray source such
as a shrouded x-ray tube generally indicated at 108, and at the
other end a receptor housing 110 enclosing an imaging x-ray
receptor.
[0041] When operating in a CT mode, the systems of FIGS. 1A-1C
immobilize a patient's breast between compression elements 104a and
104b. Unit 104 is raised or lowered together with axle 102 to the
height of the breast while the patient is upright, e.g., standing
or sitting. The patient leans toward unit 104 from the left side of
the system as seen in 113, and a health professional, typically an
x-ray technician, adjusts the breast between compression elements
104a and 104b while pulling tissue to the right in FIG. 1B and
moving at least one of compression elements 104a and 104b toward
the other to immobilize the breast and keep it in place, with as
much as practicable of the breast tissue being between the
compression elements 104a and 104b, In the course of taking x-ray
measurements representing CT projection x-ray images CTp, from
which to reconstruct images CTr of respective breast slices, gantry
106 rotates about the central axis of axle 102 while the breast
remains immobilized in unit 104, imaging x-ray receptor 112 inside
housing 110 may remain fixed relative to x-ray tube 108 during the
rotation of gantry 106. In another example, the x-ray receptor 112
may rotate or pivot within the housing 110. A pyramid shaped beam
of x-rays from tube 108 traverses the breast immobilized in unit
104 and impinges on imaging receptor 112, which in response
generates a respective two-dimensional array of pixel values
related to the amount of x-ray energy received for each increment
of rotation at respective pixel positions in an imaging plane of
the receptor. These arrays of pixel values for images CTp are
delivered to and processed by a computer system to reconstruct
slice images CTr of the breast. Gantry 106 may be configured for
motorized movement toward column 100, to facilitate the x-ray
technician's access to the patient's breast for positioning the
breast in unit 104, and away from column 100 to ensure that x-ray
tube 108 and imaging receptor 112 inside housing 110 can image the
appropriate breast tissue. Alternatively, gantry 106 can maintain a
fixed distance from column 100, to the left of the position seen in
FIG. 1A, so that the imaging x-ray beam can pass through as much as
practical of the breast immobilized in unit 104, in which case
there would be no need for a mechanism to vary that distance.
[0042] FIG. 1C includes many of the same elements, components, and
functionality as the example depicted in FIGS. 1A and 1B.
Additionally, FIG. 1C includes a column 1000 that pivots from a
vertical position about a pivot axis 1001 of a pivoting support
1002, for example over an angle .alpha. as illustrated. The angle
.alpha. may be up to about 5.degree., up to about 10.degree., up to
about 15.degree., or higher. This pivoting allows the patient to
lean forward against a shield 1004, which may increase patient
comfort and protect the patient from the rotating components. A
rotating C-arm 1006 can carry an x-ray source 108 emitting x-ray
beam 109, and an x-ray imaging receptor housing 110, and can be
moved up and down column 1000 to accommodate patients of different
heights. Shield 1004 shields the patient from the x-ray source 108
as it rotates around breast compression unit 104, and also shields
the patient from any rotation of x-ray imaging receptor housing 110
containing an imaging receptor 112. Shield 1004 further acts to
stabilize the patient leaning against it, and may include handles
that the patient may hold to further facilitate patient comfort and
stability. Shield 1004 can surround the rotational trajectory of
source 108 and housing 110, and may include a front portion 1004b
that has an opening for the patient's breast, which opening may be
sufficiently large to allow a health professional to reach in to
adjust the breast as it is being compressed. Shield 1004a surrounds
compression unit 104 that may include two compression elements
104a, 104b, as discussed above. Shield 1004a may also include a
portion 1004b that also protects the patient from motion of gantry
1006. Some or all of portion 1004b may be removable, particularly
for taking mammograms. Further, as the patient leans against the
imaging system, the patient also directly applies her weight
against the breast compression unit 104.
[0043] FIG. 2 depicts a front elevation an imaging system showing
rotational movement of a radiation source. CT scanning typically
involves a rotation of the source 110 and receptor 108 through an
angle of about 180.degree. plus the angle subtended by the imaging
x-ray beam, and in certain examples a rotation through a greater
angle, e.g., about 360.degree., as shown in FIG. 2. Tomosynthesis
scans similarly involve rotation of the source 110, although
generally across a smaller angle, such as about 15.degree.. The
source 110 and receptor 108 rotate around breast about the central
axis of the axle 102. The path along which the source 110 and the
receptor 108 rotate may be called an imaging arc 116. The imaging
arc 116 has a radius R.sub.I that extends from a center point
C.sub.I which is located at the central axis of the axle 102 to the
source, such as the x-ray tube 108. As such, a simplified
representation of the of curvature (k.sub.I) of the imaging arc 116
is 1/R.sub.I. In practice, the rotation may only be performed over
a portion of the imaging arc 116, but the radius R.sub.I, center
point C.sub.I, and curvature (k.sub.I) of the arc 116 remains the
same. Another position of the source 110' and the receptor 108' are
depicted in FIG. 2 for illustrative purposes.
[0044] As discussed above, a challenge in upright breast CT and/or
tomosynthesis is how to immobilize the breast. In some cases, for
various reasons, little or no compression of the breast may be
desirable. In other cases, it may be desirable to compress or
otherwise act on the breast, for example so that breast tissue can
be pulled away from patient's chest wall and securely retained in
unit 104 for imaging. Accordingly, and to generally increase
patient comfort, one or both of compression elements 104a and 104b
are shaped in a manner designed to hold the breast for CT and/or
tomosynthesis imaging while keeping the breast shaped so as to
allow for close to equal path lengths of x-rays at least within
individual slices. For example, the compression elements 104a and
104b may have, on the compression surfaces of the elements 104a,
104b, a curvature in the shape of an arc that shares the same
center point C.sub.I as the imaging arc 116. This curvature is
depicted more clearly in FIG. 3C. In such an example, the arc of
the compression surface and the imaging arc 116 are concentric. In
another example, the curvature of the compression surfaces of the
compression elements 104a and 104b substantially matches the
curvature of the imaging arc 116. In some examples, the curvature
of the compression surfaces may be greater than or less than the
curvature of the imaging arc 116. Compression elements 104a and
104b may be removably secured via a bracket so that different sets
of compression elements can be used to accommodate differently
sized or shaped breasts. Different degrees of breast compression
can be used as selected by a health professional operating the
systems described herein.
[0045] An example of a breast compression element 300 is shown in
multiple views shown in FIGS. 3A-3I. FIGS. 3A-3I are described
concurrently. The breast compression element 300 may be utilized as
a breast compression paddle or surface or a breast support
platform. In general, surfaces of the breast compression element
300 are described as depicted in the figures (e.g., "top," bottom,"
"left," etc.). These general terms are utilized for clarity only to
distinguish the various surfaces from each other. For instance, in
FIGS. 3A-3I, the compression surface may be referred to as the
bottom surface 318 and the non-compression surface may be referred
to as the top surface 308. The breast compression element 300
includes a curved front surface 302, a curved left surface 304, a
curved right surface 306, a top surface 308, a back surface 310,
and a curved bottom surface 318. The breast compression element 300
may be manufactured from a material that is designed to cause
minimal interference with the radiation beam passing through the
breast compression element 300, such as a radiolucent material. For
example, the breast compression element 300 may be made from a
polycarbonate material, a carbon fiber material, or other similar
materials. The breast compression element 300 may be hollow, solid,
or partially filled. The back surface 310 of the breast compression
element 300 is attached to a bracket 312. The bracket 312 may then
be removably attached to an imaging system, as discussed above. The
bracket 312 and/or a surface of the compression element 300 may
have a gas inlet port 313 that is in fluidic communication with an
interior of the compression element 300. Heated fluid, such as warm
air or gas, may be injected into the compression element 300 via
the gas inlet port to warm the compression element 300 before
and/or during contact with the breast. Certain compression elements
300 may define a plurality of ports to allow the fluid to escape
into a gap 316 between a flexible material 314 and the more rigid
structure of the breast compression element 300.
[0046] In some implementations, the breast compression element 300
is surrounded by a flexible material 314. The flexible material 314
is generally a thin-film material and may be made from a variety of
materials, e.g., a shrink-wrap material. In some examples, the
flexible material 314 has a high tensile strength and limited
stretching characteristics when surrounding the breast compression
element 300. In an example, the flexible material 314 is in contact
with and surrounds the right surface 306, the left surface 304, and
the top surface 308. In such an example, the flexible material 314
spans from the right surface 306 to the left surface 304, defining
a gap 316 between the flexible material 314 and the bottom surface
318. For instance, the flexible material 314 is spaced apart from
the concave bottom surface 318 to define the gap 316. When the
flexible material 314 spans from the right surface 306 to the left
surface 306, the flexible material 314 is tensioned such that the
portion of the flexible material 314 spaced apart from the concave
bottom surface 318 is less flexible then when in a non-tensioned
state, but without being rigid. In some examples, the flexible
material 314 also surrounds the curved front surface 302. The
flexible material 314 may also surround at least a portion of the
back surface 310.
[0047] In operation, the breast compression element 300 is pressed
against the breast such that the flexible material 314 first
contacts the breast. In one embodiment, as the breast compression
element 300 continues to compress the breast, the breast forces the
flexible material 314 closer to the bottom surface 318 until the
flexible material ultimately contacts the bottom surface 318, thus
eliminating the gap 316. By having the flexible material 314 first
contact the breast, patient comfort may increase and a more uniform
compression may be achieved as the flexible material 314 contours
to the shape of the breast during compression.
[0048] The shape of the breast compression element 300 also
provides additional benefits in imaging systems. As can be seen
from FIGS. 3A-3I, the breast compression element 300 is
substantially symmetric about plane S, shown in FIG. 3G. The left
surface 304 and the right surface 306 are generally semicylindical.
The height H.sub.S of the semicylindrical shape of the left surface
304 and the right surface 306 is defined by the back surface 310
and the beginning of the front surface, as shown in FIG. 3G. The
semicylindrical shape of the left surface 304 and the right surface
306 has a radius R.sub.S, as shown in FIG. 3C. In some examples,
the radius R.sub.S is between about 1-2 inches. In other examples,
the radius R.sub.S is between about 1.2 to about 1.8 inches. In yet
further examples, the radius is R.sub.S is between about 1.4 to
about 1.6 inches.
[0049] The front surface 302 is shaped substantially as two
half-hemispheres connected by a partial semicylinder. One of the
half-hemispheres is attached to the front of the left surface 304
and the other half-hemisphere is attached to the right surface 306.
In some examples, the radius of the half-hemispheres R.sub.H is the
same as the radius R.sub.S of the semicylindrical shape of the left
surface 304 and the right surface 306, as shown in FIG. 3C. The two
half-hemisphere shapes are connected by a partial semicylinder
having a height H.sub.F defined by distance between the front-most
points of the two half-hemisphere shapes of the front surface 302,
as shown in FIG. 3C. The partial semicylinder has a curved surface,
which forms the front edge of the bottom surface 318. Because of
the curved surface of the partial semicylinder, the partial
semicylinder has a variable radius R.sub.F, with its maximum radius
R.sub.Fmax occurring at the inner edges of the two half-hemisphere
shapes and its minimum radius R.sub.Fmin occurring at the geometric
center of the front surface 302, as shown in FIG. 3C.
[0050] The bottom surface 318 is a curved substantially smooth
surface in the shape of an arc. As discussed above, the center
point C.sub.B of the bottom surface 318 arc may be the same as the
center point C.sub.I of the imaging arc. In such an example, the
arc of the bottom surface 318 is concentric with the imaging arc.
In another example, the curvature (k.sub.B) of the bottom surface
318 may be equal to the curvature (k.sub.I) of the imaging arc. In
that example, the curvature (k.sub.B) of the bottom surface 318 is
equal to the inverse of the arc radius R.sub.B of the bottom
surface 318. In some examples, the curvature (k.sub.B) of the
bottom surface, may be greater than or less than the curvature
(k.sub.I) of the imaging arc. For instance, the ratio of the
curvature (k.sub.B) of the bottom surface to the curvature
(k.sub.I) of the imaging arc may be about 5:1 or greater. The
bottom surface 318 is connected to the left surface 304, the right
surface 306, the back surface 310, and the front surface 302.
[0051] The top surface 308 is a substantially planar surface
connected to the left surface 304, the right surface 306, the back
surface 310, and the front surface 302. In other examples, the top
surface 308 may be a curved surface having a shape similar to the
curved bottom surface 318. For instance, the top surface 308 may be
arc-shaped with a center point of the top surface 308 arc being the
same as the center point C.sub.I of the imaging system and the
center point C.sub.B of the bottom surface 318. In such an example,
the imaging arc, the arc of the top surface 308, and the arc of the
bottom surface 318 are all concentric. Thus, the thickness of the
compression element 300 remains consistent for a larger portion of
the breast compression element 300 relative to the imaging source
as it sweeps across the imaging arc. In other examples, the top
surface 308 may have a curvature (k.sub.T) equal to that of the
curvature (k.sub.B) of the bottom surface 318 and/or the curvature
(K.sub.I) of the imaging arc.
[0052] The compression element 300 is substantially free from sharp
edges. For example, the transitions between the surfaces of the
compression element 300 may all be smooth and therefore free from
sharp edges. The transition between the left surface 304 and the
top surface 308 occurs at the location where the tangent plane to
the semicylindrical shape of the left surface 304 intersects and is
parallel to the plane of the of the top surface 308. Similarly, the
transition between the right surface 306 intersects and the top
surface 308 occurs at the location where the tangent plane to the
semicylindrical shape of the right surface 306 is parallel to the
plane of the of the top surface 308. The transition between the
front surface 302 and the top surface 308 occurs where the tangent
planes of the half-hemisphere shapes and the partial semicylinder
shape of the front surface 302 intersect and are parallel with the
plane of the top surface 308. The transitions between the front
surface 302 and the left surface 304 and the right surface 306,
respectively, also occur at locations where the tangent plane of
the semicylindrical shapes of the left surface 304 and the right
surface 306 intersect and are parallel to the tangent planes of the
half-hemisphere shapes of the front surface 302. Further, the
transition between the front surface 302 and the bottom surface 318
occurs at a location such that the curvature of the bottom edge of
the front surface 302 matches the curvature of the bottom surface
318. The transition between the front surface 302 and the bottom
surface 318 is also at a location where the tangent plane of the
partial semicylinder shape of the front surface is parallel to the
tangent plane of the curved bottom surface 318. The transitions
between the bottom surface 318 and the left surface 304 and the
right surface 306, respectively, also occur at locations where the
tangent plane of the semicylindrical shapes of the left surface 304
and the right surface 306 intersect and are parallel to the tangent
planes of the curved bottom surface 318. Accordingly, each those
transitions are smooth and do not include any sharp edges.
[0053] The smooth surfaces and transitions between the surfaces
provide for additional comfort of the patient and improved image
quality. For instance, the smooth curved bottom surface 318 allows
for a more comfortable compression procedure for the patient. The
smooth transitions between the surfaces also increase the comfort
of the patient, particularly in systems that involve tilting of the
imaging system, such as depicted in FIG. 1C. In such systems, the
chest wall of the patient is pressed against the front surface 302
of the compression element 300 could cause significant discomfort.
The structure of the compression element 300 is also suited to
support the weight of the patient that is applied to the
compression element 300 during scanning in a tilted system.
[0054] The transitions between adjacent surfaces are described
herein as smooth and substantially free from sharp edges. Sharp
edges may cause areas of high stress on the shrink wrap that covers
a significant portion of the breast compression element 300, thus
increasing the likelihood of ripping. Further, sharp edges may also
interfere with the x-ray radiation and cause discomfort for the
patient. The smooth transitions reduce these undesired effects. In
an example, a "sharp edge" may be defined as an intersection at a
defined line or line segment of two essentially planar surfaces. In
another example, a sharp edge may be defined as an edge between two
surfaces where the angle between the tangent plane of the first
surface and the tangent plane of the second surface is less than
about 120 degrees at the location of intersection between first and
second surfaces. For example, although majority of the various
surfaces discussed above all intersect at location substantially
free from sharp edges, the intersection between the back surface
310 and the back surfaces need not be a smooth transition. For
instance, in the example depicted in FIGS. 3A-3I, the transition
between the back surface 310 and the left surface 304, the right
surface 306, the top surface 308, and the bottom surface 318 each
include a sharp edge. As an example, as depicted, the plane of the
back surface 310 is perpendicular to the plane of the top surface
308.
[0055] FIG. 3I depicts the flexible material 314 removed from the
remainder of the breast compression element 300 for clarity. In
some examples, however, the flexible material 314 is not removable
from the remainder of the compression element 300. For instance,
where the flexible material 314 is a shrink-wrap material, the
shrinking process is performed when the flexible material 314 is
covering the remainder of the compression element 300. Thus, in
such an example, the flexible material 314 is not easily
removed.
[0056] In examples where the flexible material 314 is a shrink-wrap
material or other similar tight-fitting material, the flexible
material 314 may be applied to the compression element 300 prior to
conducting a breast imaging procedure. Heat is then applied to the
compression element 300 and the flexible material 314 to cause the
flexible material to shrink and increase the tension of the portion
of the flexible material 314 spanning the gap 316. In some
examples, the heating process may occur at a time just prior to the
breast imaging procedure in order to warm the breast compression
element 300 to increase patient comfort as the breast is
compressed. Additionally, the flexible material 314 is
advantageously disposable. As such, after use with a first patient,
the flexible material 314 may be removed and a new flexible
material 314 may be applied for a subsequent patient. This may
eliminate the need to clean or otherwise treat the surface of the
breast compression element 300 between patients.
[0057] FIG. 4A depicts a schematic view of an imaging system using
the breast compression element of FIGS. 3A-3I. FIG. 4B depicts a
perspective view of a breast imaging system of FIG. 4A and is
described concurrently with FIG. 4A. In the depicted system, a
patient's breast 410 is immobilized for x-ray imaging between two
breast compression elements, namely a breast support platform 412
and a compression paddle 416. Platform 412 can be the upper surface
of a housing 414. Either one or both of the platform 412 and the
compression paddle 16 may be made in the shape of the of the breast
compression element depicted in FIGS. 3A-3I. Platform 412 and
paddle 416 form a breast immobilizer unit 20 that is in a path of
an imaging beam 422 emanating from x-ray source 424. For instance,
where the platform 412 incorporates the breast compression elements
depicted in FIGS. 3A-31, a radiographic detector or image receptor
426 may be incorporated into a hollow portion of the breast
compression element. Beam 422 impinges on the image receptor 426
that is in housing 414, which in some examples may be at least a
portion of the breast compression element. Immobilizer 420 and
housing 414 are supported on an arm 428. X-ray source 424 is
supported on an arm 430. For mammography, support arms 428 and 430
can rotate as a unit about an axis such as at 430a between
different imaging orientations such as CC and MLO, so that the
system can take a mammogram projection image at each orientation.
Image receptor 426 remains in place relative to housing 414 while
an image is taken. Immobilizer 420 releases breast 410 for movement
of arms 428 and 430 to a different imaging orientation. For
tomosynthesis, support arm 428 stays in place, with breast 410
immobilized and remaining in place, while at least source support
arm 430 rotates source 424 relative to immobilizer 420 and breast
410 about an axis such as 30a. The system takes plural
tomosynthesis projection images of breast 410 at respective angles
of beam 422 relative to breast 410. Concurrently, image receptor
426 may be tilted relative to breast platform 412 in sync with the
rotation of source support arm 430. The tilting can be through the
same angle as the rotation of source 424, but may be through a
different angle, selected such that beam 422 remains substantially
in the same position on image receptor 426 for each of the plural
images. The tilting can be about an axis 432a, which can but need
not be in the image plane of image receptor 426. A tilting
mechanism 434, which also is in housing 414 or is otherwise coupled
with receptor 426, can drive image receptor 426 in a tilting
motion. Axes 430a and 432a extend left-right as seen in FIG. 4A.
For tomosynthesis imaging and/or CT imaging, breast platform 412
can be horizontal or can be at an angle to the horizontal, e.g., at
an orientation similar to that for conventional MLO imaging in
mammography. The system of FIGS. 4A-4B can be solely a mammography
system, a CT system, or solely a tomosynthesis system, or a "combo"
system that can perform multiple forms of imaging. An example of
such a combo system is been offered by the assignee hereof under
the trade name Selenia Dimensions.
[0058] When the system is operated, image receptor 426 produces
imaging information in response to illumination by imaging beam
422, and supplies it to image processor 434 for processing to
generate breast x-ray images. A fluid control unit 436 connects
with the compression paddle to provide warm air into the
compression paddle 416 to increase the comfort of the patient,
and/or heat or pressurize the flexible material surrounding the
paddle, as described heat. In an example, the fluid control unit
436 connects via a quick-release snap-on connection 448. A system
control and work station unit 438 controls the operation of the
system and interacts with a user to receive commands and deliver
information including processed-ray images.
[0059] Image processing with a compression paddle having a
non-planar compression surface, however, raises additional
challenges due to the shape of the paddle. For instance, due to the
shape of the paddle being non-planar or have in a non-uniformity on
the compression surface, the breast is not compressed to a uniform
thickness. Accordingly, radiation that passes through the curved
paddle and the compressed breast is attenuated differently. As a
result, bright spots and non-uniformity of the resultant image
occurs. The present technology provides for a solution for
processing an image when using a curved paddle to correct for the
differences in attenuations. As an example, FIG. 5A shows an
uncorrected image of a breast compressed with a curved paddle, such
as those described herein or those cited in Publication No. WO
2014/176445, which is hereby incorporated herein by reference in
its entirety. As can be seen from the image, the upper portion of
the breast appears darker than normal and the center of the breast,
particularly towards the chest wall, appears brighter than normal.
By using the image processing techniques discussed herein, the
image can be corrected to the corrected image shown in FIG. 5B. As
can be seen from the image in FIG. 5B, the brightness appears more
uniform and the underlying tissue composition of the can be more
easily discerned.
[0060] In some examples, the image processing techniques of the
present technology involves generating a correction map for a
particular curved paddle having a non-planar compression surface.
The generation of the correction map may only need to be performed
once for a particular curved paddle shape and imaging system. For
instance, the same correction map may be utilized for all systems
of a given type using the particular curved paddle. Once a
correction map has been generated for the particular curved paddle,
the correction map can be applied to raw image data or an image
dataset taken of a breast compressed with the particular curved
paddle to generate a corrected image. The correction map may also
be adjusted for a particular scan configuration, such as
tomosynthesis imaging, two-dimensional imaging, CT imaging,
mediolateral-oblique imaging, craniocaudal (CC) imaging, or other
imaging configurations and orientations, including combinations
thereof.
[0061] FIG. 6A depicts a method 600 for generating a correction map
for image processing for curved paddles. At operation 602, the
paddle is filled with a liquid such as water. For instance, the
paddle may be hollow and have an opening on the top of the paddle,
among other positions, such that the paddle may be filled. For
instance, the paddle may include a recess on at least a top portion
of the paddle to receive the liquid. The recess may be generally
open or may include an opening on a potion to access the recess.
The recess may generally be on the top portion of the paddle such
that the liquid may fill a portion which corresponds to the
compression surface. Depending on the paddle, certain connection
slots or other apertures in the paddle may need to be plugged such
that the liquid does not flow out the paddle. For curved paddles
that are not hollow, the paddle may be dipped in water in a
substantially radiolucent container. At operation 604, the paddle
is placed on a substantially radiolucent surface proximate to the
detector. For instance, the paddle may be placed on a Lucite block
having about generally a 4 centimeter thickness. In some examples,
the substantially radiolucent surface covers the entire imaging
area of the detector.
[0062] Radiation, such as x-ray radiation, is passed through the
filled paddle and the substantially radiolucent surface at
operation 606. The radiation is then detected by the detector at
operation 608. The emission and detection of radiation may occur
during a standard 2D imaging mode. In some examples, an auto-kV
mode may be used, but other modes may also be suitable. The
radiation used for calibration or generation of the correction map
may be ay one or more of a scout exposure, a full mammographic
exposure, or one or more tomosynthesis exposures. An image, or
image data, is the generated form the detected radiation at
operation 610. The image generated is indicative of the curved
paddle shape. An example image produced at operation 610 is
depicted in FIG. 6B.
[0063] From the image data produced in operation 610, an average
pixel value is determined at operation 612. The average pixel value
may be determined across the entire image. Based at least one
average pixel value, the correction map is generated at operation
614. The correction map may be generated by dividing the pixel
values of the image data generated in operation 610 by the average
pixel value determined in operation 612 to generate a normalized
correction map. In some examples, the correction map is further
modified by generating a series of polynomial fits to represent the
correction map. For instance, the correction map may be considered
to be a matrix, where the elements of the matric represent
correction values for a corresponding pixel of the detector. Each
element of the matrix includes a value for scaling a brightness
value of the corresponding pixel of the detector. Similarly, the
correction map may also be considered to be a set of columns (x) of
pixels or points and a rows (y) of pixels or points. In such an
example, for each column (x), pixels along the rows (y) are
selected. In selecting the pixels, some pixels may skipped, such as
skipping by ten pixels for each selection. The values for the
selected pixels are then fit to a polynomial function, such as a
4th order polynomial. For each of the y-values, the polynomial
fitting may be used to generate a fitted image or a fitted
correction map. The fitted correction map may also be smoothed
using an averaging technique, such as a boxcar averaging method. In
addition, the smoothed, fitted correction map may be scaled down.
In some examples, the scaling may be by a factor of 4 and may be
done using decimation (e.g., skipping points). Other scaling
factors are contemplated. The scaled, smoothed, and fitted
correction map may then be stored as a final correction map to be
used in image processing. By fitting the correction map to a
polynomial, image noise or other local irregularities are
effectively removed from the final correction map. Once the
correction map has been generated, it can be used to correct image
data taken using the curved paddle for which the correction map was
generated. For example, the image shown in FIG. 6C is a corrected
version of the image shown in FIG. 6B using the correction map
generated from the image in FIG. 6B.
[0064] FIG. 7 depicts a method 700 for image processing for curved
paddles utilizing a correction map, such as the one generated by
method 600 depicted in FIG. 6A. At operation 702, image data is
received. The image data may be received from detector of the
imaging system. At operation 704, a correction map associated with
the compression paddle is used to compress the breast during
imaging. In some examples, the correction map may be stored locally
or remotely from the imaging system. The correction map may be
further altered or corrected prior to its use in correcting the
image data received in operation 702. For example, the correction
map may be scaled based on an image size for the image data
received in operation 702. The scaling may be to upscale the
correction map to the current image size using a linear
interpolation technique. The correction map may also be smoothed
using an averaging technique, such as a boxcar averaging technique.
The correction map may also be modified by applying a squeeze
factor. The squeeze factor is an adjustment to the correction map
that is paddle dependent. The squeeze factor allows for adjustment
of the magnitude of the correction provided by the correction map.
The correction map may also be modified to correct for a projection
angle and a paddle shift. Such a correction shifts the correction
map depending on the projection angle and the actual paddle shift.
In addition, the correction map may also be modified to correct for
magnification. For example, the correction map may be modified
based on the paddle height used for imaging as compared to the
paddle height used during calibration. For instance, in examples
where a 4 cm Lucite block is used as the substantially radiolucent
surface in operation 604 of the calibration method 400, the
calibration height is 4 cm. The height may be measured to any point
on the paddle as long as the measurement is consistent when
comparing heights.
[0065] At operation 706, the image data received at operation 702
is corrected based on the correction map accessed in operation 704.
In some examples, the image data is corrected based on the
correction map as modified according to the techniques discussed
above. The image data may be corrected on a pixel-by-pixel basis.
The image may be corrected by multiplying or dividing the image
data by the correction map. For instance, each pixel of the image
data may be multiplied or divided by the corresponding pixel value
in the correction map. The correction to the image data may also be
a correction to the raw image data prior to generating an actual
image of the breast being imaged. At operation 708, a corrected
image is generated from the corrected image data. In sonic
examples, such as with breast CT and/or tomosynthesis techniques,
the corrected image may be part of an image dataset that includes a
series of images. Generating the corrected image may also include
displaying the corrected image on a display screen or other medium
for viewing and analysis by a physician or technician.
[0066] In some instances, further correction to the image data may
be desired for image areas near the chest wall, such as about 2 cm
from the chest wall. For example, while the above corrections work
well for imaging portions of the breast in contact with the paddle,
the corrections may be further improved for portions of the breast
not in contact with the paddle. When the breast is not in contact
with the paddle, an air gap is formed between the breast and the
paddle. The x-ray attenuation is therefore different for portions
of the breast in contact with the paddle and portions of the breast
not in contact with the paddle. Portions of the breast not in
contact with the paddle generally occur near the chest wall. The
additional correction for imaging the breast portions not in
contact with the paddle may be referred to as an air area
correction (AAC).
[0067] The AAC may be a further correction in addition to already
utilized corrections or other image processing techniques to
further help visualize the breast. As an example, the AAC may be a
further correction to at least one of a multiscale image
decomposition technique utilized in processing the image and skin
line detection or correction techniques. For instance, the skin
line correction may be utilized to equalize the pixel values near
the skin edge in order to improve visualization of the breast near
the skin line. The AAC may be an additional correction near the
chest wall to correct for the brightness changes due to the air gap
between the paddle and the breast. As an example, the AAC may
utilize a correction based on the difference between the pixel
value and a threshold value. For instance, the adjustment value may
be based on a value, representing the difference between the pixel
value and a threshold value, multiplied by a slope value at one or
more image decomposition scales. In addition, the slope may be
represented by a weighting factor function based on the pixel
location. After the AAC correction according to the above
techniques, the attenuation in the small local vertical area near
the chest wall is corrected and the final processed images do not
appear as having a non-uniformity, such as a slightly dark area,
near the chest wall.
[0068] FIG. 8 depicts a method for image processing for a paddle
providing inconsistent compression. For example, with a paddle
having a flexible element, such as breast compression element 300
discussed above, each breast will not be compressed in the same
manner. Accordingly, additional improvements may be made in
addition to the one-time calibration map solution discussed above.
For example, correction to the images taken with a paddle providing
inconsistent compression may be determined on the fly for each
image taken of the breast.
[0069] At operation 802, image data is received for an image of the
breast. The image data may be received from a detector. At
operation 804, pixel values in the image data are identified. In
some examples, an average pixel value may also be determined. Based
on the pixel values in the image data, a low frequency correction
is determined at operation 806. The low frequency correction may be
generated in the form of a correction map or a low frequency
function. The low frequency correction is to correct for the
background variations in brightness, while not Obscuring any of the
higher detail elements of the image, such as vascular elements or
other tissue composition of the breast. Based on the low frequency
correction, a corrected image may then be generated in operation
808.
[0070] FIG. 9 depicts one example of a suitable computing device
1400 that may be coupled to the scanning systems discussed herein.
The computing device 1400 is a suitable operating environment in
which one or more of the present examples can be implemented. This
operating environment may be incorporated directly into a scanning
system, or may be incorporated into a computer system discrete
from, but used to control or process data from, the scanning
systems described herein. This is only one example of a suitable
operating environment and is not intended to suggest any limitation
as to the scope of use or functionality. Other well-known computing
systems, environments, and/or configurations that can be suitable
for use include, but are not limited to, personal computers, server
computers, hand-held or laptop devices, multiprocessor systems,
microprocessor-based systems, programmable consumer electronics
such as smart phones, network PCs, minicomputers, mainframe
computers, tablets, distributed computing environments that include
any of the above systems or devices, and the like.
[0071] In its most basic configuration, operating environment 1400
typically includes at least one processing unit 1402 and memory
1404. Depending on the exact configuration and type of computing
device, memory 1404 (storing, among other things, instructions to
perform the measurement acquisition, processing, and visual
representation generation methods disclosed herein) can be volatile
(such as RAM), non-volatile (such as ROM, flash memory, etc.), or
some combination of the two. This most basic configuration is
illustrated in FIG. 9 by dashed line 1406. Further, environment
1400 can also include storage devices (removable, 1408, and/or
non-removable, 1410) including, but not limited to, solid-state
devices, magnetic or optical disks, or tape. Similarly, environment
1400 can also have input device(s) 1414 such as touch screens,
keyboard, mouse, pen, voice input, etc., and/or output device(s)
1416 such as a display, speakers, printer, etc. Also included in
the environment can be one or more communication connections 1412,
such as LAN, WAN, point to point, Bluetooth, RF, etc.
[0072] Operating environment 1400 typically includes at least some
form of computer readable media. Computer readable media can be any
available media that can be accessed by processing unit 1402 or
other devices comprising the operating environment. By way of
example, and not limitation, computer readable media can comprise
computer storage media and communication media. Computer storage
media includes volatile and nonvolatile, removable and
non-removable media implemented in any method or technology for
storage of information such as computer readable instructions, data
structures, program modules or other data. Computer storage media
includes, RAM, ROM, EEPROM, flash memory or other memory
technology, CD-ROM, digital versatile disks (DVD) or other optical
storage, magnetic cassettes, magnetic tape, magnetic disk storage
or other magnetic storage devices, solid state storage, or any
other tangible and non-transitory medium which can be used to store
the desired information.
[0073] Communication media embodies computer readable instructions,
data structures, program modules, or other data in a modulated data
signal such as a carrier wave or other transport mechanism and
includes any information delivery media. The term "modulated data
signal" means a signal that has one or more of its characteristics
set or changed in such a manner as to encode information in the
signal. By way of example, and not limitation, communication media
includes wired media such as a wired network or direct-wired
connection, and wireless media such as acoustic, RF, infrared and
other wireless media. Combinations of the any of the above should
also be included within the scope of computer readable media,
[0074] The operating environment 1400 can be a single computer
operating in a networked environment using logical connections to
one or more remote computers. The remote computer can be a personal
computer, a server, a router, a network PC, a peer device or other
common network node, and typically includes many or all of the
elements described above as well as others not so mentioned. The
logical connections can include any method supported by available
communications media. Such networking environments are commonplace
in hospitals, offices, enterprise-wide computer networks, intranets
and the Internet.
[0075] In some examples, the components described herein comprise
such modules or instructions executable by computer system 1400
that can be stored on computer storage medium and other tangible
mediums and transmitted in communication media. Computer storage
media includes volatile and non-volatile, removable and
non-removable media implemented in any method or technology for
storage of information such as computer readable instructions, data
structures, program modules, or other data. Combinations of any of
the above should also be included within the scope of readable
media. In some examples, computer system 1400 is part of a network
that stores data in remote storage media for use by the computer
system 1400.
[0076] FIG. 10 is an example of a network 1500 in which the various
systems and methods disclosed herein may operate. In examples, a
client device, such as client device 1502, may communicate with one
or more servers, such as servers 1504 and 1506, via a network 1508.
In examples, a client device may be a laptop, a personal computer,
a smart phone, a PDA, a netbook, or any other type of computing
device, such as the computing device in FIG. 9. In examples,
servers 1504 and 1506 may be any type of computing device, such as
the computing device illustrated in FIG. 9. Network 1508 may be any
type of network capable of facilitating communications between the
client device and one or more servers 1504 and 1506. Examples of
such networks include, but are not limited to, LANs, WANs, cellular
networks, and/or the Internet.
[0077] In examples, processing of data and performance of the
methods described herein may be accomplished with the use of one or
more server devices. For example, in one example, a single server,
such as server 1504 may be employed to assist in processing data
and performing the methods disclosed herein. Client device 1502 may
interact with server 1504 via network 1508. In further examples,
the client device 1502 may also perform functionality disclosed
herein, such as scanning and processing data, which can then be
provided to servers 1504 and/or 1506.
[0078] In alternate examples, the methods disclosed herein may be
performed using a distributed computing network, or a cloud
network. In such examples, the methods disclosed herein may be
performed by two or more servers, such as servers 1504 and 1506.
Although a particular network example is disclosed herein, one of
skill in the art will appreciate that the systems and methods
disclosed herein may be performed using other types of networks
and/or network configurations. Further, the data sent to the
servers and received from the servers may be encrypted. The data
may also be stored in an encrypted manner both locally and on the
servers.
[0079] This disclosure described some examples of the present
technology with reference to the accompanying drawings, in which
only some of the possible examples were shown. Other aspects can,
however, be embodied in many different forms and should not be
construed as limited to the examples set forth herein. Rather,
these examples were provided so that this disclosure was thorough
and complete and fully conveyed the scope of the possible examples
to those skilled in the art.
[0080] Although specific examples were described herein, the scope
of the technology is not limited to those specific examples. One
skilled in the art will recognize other examples or improvements
that are within the scope of the present technology. Therefore, the
specific structure, acts, or media are disclosed only as
illustrative examples. Examples according to the technology may
also combine elements or components of those that are disclosed in
general but not expressly exemplified in combination, unless
otherwise stated herein. The scope of the technology is defined by
the following claims and any equivalents therein.
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